Total Suspended Particulates (TSP)
suspended particulates (TSP) are small airborne particles
such as dust, fume and smoke with diameters less than 100
micrometres. They are emitted from various sources including
power stations, construction activities, incineration and
portion, which are known as the respirable suspended particulates
below, are of greater health concern. The coarse particles
are mainly related to soiling and dust nuisance.
of TSP in 1996 are depicted in Figure
6. The concentrations remained high throughout the territory
although a slight decrease in the overall concentration was
noted when compared with the figures of 1995. Six out of the
nine monitoring stations recorded violation of the annual
air quality objective. The highest annual level at the street
site of Mong Kok was almost 78% above the limit. Due to closer
proximity to emissions from vehicles and surrounding construction
activities, it also recorded two violations of the 24-hour
AQO limit. Same as previous years, Sha Tin recorded the lowest
annual level which was about 86% of the permissible limit.
Suspended Particulates (RSP)
suspended particulates (RSP) are airborne particles with diameters
of 10 micrometres or less. Apart from combustion sources,
in particular diesel vehicles, atmospheric oxidation of sulphur
dioxide and nitrogen oxides and to a less extent, the crustal
dust and marine aerosols are also a significant sources of
cause chronic and acute effects on human health, particularly
the pulmonary function, when exposed at high level as they
can penetrate deep into the lungs and cause respiratory problems.
These effects are enhanced if high RSP levels are associated
with higher levels of other pollutants, such as SO2. Smaller
particles in RSP will also have a major impact on visibility.
concentrations recorded in 1996 at various station are shown
in Figure 7. There
was one violation of the 24-hour AQO limits at Kwun Tong.
The annual RSP levels were also high. Four sites, viz., Kwun
Tong, Yuen Long, Sham Shui Po and Mong Kok, violated the annual
AQO for RSP in 1996. The highest annual level at the street
site of Mong Kok was almost 40% above the limit. Diesel vehicle
emissions were the major cause of the high RSP concentrations.
Same as TSP, Sha Tin recorded the lowest annual level of about
84% of the permissible limit.
airborne dust mainly comes from combustion of leaded petrol.
Due to the reduction of lead in petrol programme, the ambient
lead concentrations remained very low in 1996. Higher lead
content was found at the Yuen Long station. It was possibly
caused by high traffic flow and industrial activities in the